This work aims at: a) The isolation and chemical characterization of the collagenous and non-collagenous constituents of the matrix produced by a murine basement membrane tumor, the so-called EHS-sarcoma; b) Comparing the tumor matrix components with components derived from morphologically distinct (authentic) basement membranes, such as the lens capsule or the renal glomerular basement membane; c) Characterization of newly-synthesized basement membrane constituents and elucidation of their relationship to the components of the assembled basement membrane matrix; d) Investigating the antigenic properties of isolated basement membrane components or fragments as an aid to compare and to quantitate the various structural and newly-synthesized basement membrane components.